i almost faint about twice a month HELP.?

I will almost faint anywhere from 1-3 times a month i am 12 and before this happens i go blind my hearing goes away and i feel really dizzy and friends say my face goes pale and my lips turn kind of blue does anyone know what this could be it goes away after about 3-5 mins and it's been happening for about 1 and a half years and i will go to the doctor with my mom tomorrow but i would just like to know if anyone knows what it could be . btw ..i am a girl